diff --git a/gunicorn/asgi/message.py b/gunicorn/asgi/message.py
index b73e1b0b..76569579 100644
--- a/gunicorn/asgi/message.py
+++ b/gunicorn/asgi/message.py
@@ -83,6 +83,7 @@ class AsyncRequest:
         self.trailers = []
         self.scheme = "https" if cfg.is_ssl else "http"
         self.must_close = False
+        self._expected_100_continue = False
 
         self.proxy_protocol_info = None
 
@@ -474,6 +475,21 @@ class AsyncRequest:
             if header_length > self.limit_request_field_size > 0:
                 raise LimitRequestHeaders("limit request headers fields size")
 
+            if not from_trailer and name == "EXPECT":
+                # https://datatracker.ietf.org/doc/html/rfc9110#section-10.1.1
+                # "The Expect field value is case-insensitive."
+                if value.lower() == "100-continue":
+                    if self.version < (1, 1):
+                        # https://datatracker.ietf.org/doc/html/rfc9110#section-10.1.1-12
+                        # "A server that receives a 100-continue expectation
+                        #  in an HTTP/1.0 request MUST ignore that expectation."
+                        pass
+                    else:
+                        self._expected_100_continue = True
+                    # N.B. understood but ignored expect header does not return 417
+                else:
+                    raise ExpectationFailed(value)
+
             if name in secure_scheme_headers:
                 secure = value == secure_scheme_headers[name]
                 scheme = "https" if secure else "http"